Tel Aviv University Dear all, This week at the Horowitz seminar on Probability, Ergodic Theory and Dynamical Systems at Tel Aviv University we are happy to have: Speaker: Elon Lindenstrauss, Hebrew University Title: Orbit closures for some higher rank Abelian actions Date: Monday, March 28 Time: 14:30 Place: Schreiber 309 Abstract: In 1967 Furstenberg discovered that any x2, x3 closed invariant subset of R/Z is closed or finite, contrasting with the situation for sets invariant under a single endomorphism. Even earlier, Cassels and Swinnerton-Dyer have made a deep conjecture on products of linear forms that is equivalent to a rigidity statement about orbit closures of the diagonal group in SL(n,R)/SL(n,Z) (namely that they are compact iff the orbit is periodic). However, the exact classification of orbit closures can be quite tricky, even on the conjectural level. I will present some positive and negative results in this direction based mostly on joint works with U. Shapira and Z. Wang. You may also be interested in the colloquium talk by Greg Kuperberg given two hours before, from 12:15-13:15 on "What is quantum probability?", see <http://www.math.tau.ac.il/~klartagb/colloquium/colloq_280311.html> Best regards, Ron Seminar webpage: <http://www.math.tau.ac.il/~peledron/Horowitz_seminar/Horowitz_seminar.html> --------------------------------------------------------- Technion Math Net-2 (TECHMATH2) Editor: Michael Cwikel <techm@math.technion.ac.il> Announcement from: Ron Peled <peledron@gmail.com>